This invention is generally directed to organic electroluminescent (EL) devices, and more specifically, to organic EL devices with a number of excellent desired performance characteristics, and which devices are desired that are capable of providing uniform luminescence, high electroluminescent efficiency, excellent durability, and low driving voltages. The organic EL devices of the present invention contain an electron transport component comprised of triazine compounds, and which devices can be selected for use in flat-panel emissive display technologies, including TV screens, computer screens, and the like.
A simple organic EL device can be comprised of a layer of an organic luminescent material conductively sandwiched between an anode, typically comprised of a transparent conductor, such as indium tin oxide, and a cathode, typically a low work function metal such as magnesium, calcium, aluminum, or the alloys thereof with other metals. The EL device functions on the principle that under an electric field, positive charges (holes) and negative charges (electrons) are respectively injected from the anode and cathode into the luminescent layer and undergo recombination to form excitonic states which subsequently emit light. A number of prior art organic EL devices have been prepared from a laminate of an organic luminescent material and electrodes of opposite polarity, which devices include a single crystal material, such as a single crystal anthracene, as the luminescent substance as described, for example, in U.S. Pat. No. 3,530,325. However, these devices usually require excitation voltages on the order of 100 volts or greater.
An organic EL device with a multilayer structure can be formed as a dual layer structure comprising one organic layer adjacent to the anode supporting hole transport, and another organic layer adjacent to the cathode supporting electron transport and acting as the organic luminescent zone of the device. Another alternate device configuration is comprised of three separate layers, a hole transport layer, a luminescent layer, and an electron transport layer, which layers are laminated in sequence and are sandwiched between an anode and a cathode. Optionally, a fluorescent dopant material can be added to the emission zone or layer whereby the recombination of charges results in the excitation of the fluorescent.
In U.S. Pat. No. 4,539,507 there is disclosed an EL device formed of a conductive glass transparent anode, a hole transporting layer of 1,1-bis(4-p-tolylaminophenyl)cyclohexane, an electron transporting layer of 4,4xe2x80x2-bis(5,7-di-tert-pentyl-2-benzoxzolyl)stilben, and an indium cathode.
U.S. Pat. No. 4,720,432 discloses an organic EL device comprising a dual-layer hole injecting and transporting zone, one layer being comprised of porphyrinic compounds supporting hole injection and the other layer being comprised of aromatic tertiary amine compounds supporting hole transport.
U.S. Pat. No. 4,769,292 discloses an EL device employing a luminescent zone comprised of an organic host material capable of sustaining hole-electron recombination and a fluorescent dye material capable of emitting light in response to energy released by hole electron recombination. A preferred disclosed host material is an aluminum complex of 8-hydroxyquinoline, namely tris(8-hydroxyquinolinate)aluminum.
Typically, the organic EL devices with multi-layered configurations comprise an electron transport layer in contact with a cathode. This electron transport layer is intended to assist injection of electrons from the cathode into the light-emitting layer. A variety of organic electron transport materials have been employed for this purpose. A class of such electron transport materials is comprised of the metal complexes of 8-hydroxyquinoline, as disclosed in U.S. Pat. No. 4,720,432. A another class of electron transport materials for EL devices is comprised of 1,3,5-oxidiazole compounds, such as those disclosed in Japanese Journal of Applied Physics, Part 2, vol. 34, L824 (1995). Also, certain 1,3,5-triazine containing materials have been reported as being a hole blocking layer in organic EL devices, see Fink et al. in Macromolecular Symposia, vol. 125, 151 (1997).
While recent progress in organic EL research has elevated the potential of organic EL devices for widespread applications, the performance lo levels of current available devices may still be below expectations. Further, for visual display applications, organic luminescent materials should provide a satisfactory color in the visible spectrum, normally with emission maxima at about 460, 550 and 630 nanometers for blue, green and red. The aforementioned metal complexes of 8-hydroxyquinoline, such as tris(8-hydroxyquinolinate)aluminum, generally fluoresce in green or longer wavelength region. These electron transport materials may be suitable for use in EL devices with light emission in green or longer wavelength region, however, for blue-emitting EL devices they are of limited use. Although prior art electron transport materials may fluoresce in the blue region, the performance characteristics of the resulting EL devices still possess many disadvantages such as poor operation stability. Thus, there continues to be a need for electron transport materials for organic EL devices, which are suitable for the design of EL devices with satisfactory emission in the visible spectrum of from blue to longer wavelength region. There is also a need for electron transport materials, which can improve EL device operation stability and durability, and, a need for electron transport materials, which can enhance the EL charge transporting characteristics, thus lowering device driving voltages. Further, there is a need for electron transport materials for EL device comprised of a cathode comprised of a metal, such as aluminum, and which device can maintain desirable performance characteristics, such as low driving voltage, and excellent operation stability. Further, there is a need for electron transport materials, which are vacuum evaporable and form thin films with excellent thermal stability.
It is a feature of the present invention to provide improved organic EL devices with many advantages described herein.
It is another feature of the present invention to provide EL devices capable of providing satisfactory emission in the visible spectrum from blue to longer wavelength regions, for example from about 400 nanometers to about 700 nanometers, high electroluminescent efficiency, excellent durability, and low driving voltages, for example from about 10 to about 50 volts, and a luminence value of about 100 cd/m2. In another feature of the present invention there are provided organic EL devices comprising an electron transport component comprised of specific triazine compounds, especially those containing biphenyl groups.
Further, in an feature of the present invention there are provided organic EL devices comprised of an anode and a cathode, and an organic luminescent medium containing an electron transport component comprised of triazine compounds, or comprised of a triazine electron acceptor and an amine electron donor connected by a polarizable linkage, such as an aromatic or aryl group.
In another feature of the present invention there are provided organic EL devices comprised of a supporting substrate of, for example, glass, an anode, a buffer layer, a hole transport layer, an electron transport layer, and in contact therewith a metal cathode, wherein the electron transport layer is comprised of an electron transport component comprised of specific novel triazine compounds.
Yet in another feature of the present invention there are provided organic EL devices comprised of a supporting substrate of, for example, glass, an anode, an optional buffer layer, a hole transport layer, a light emitting layer, an electron transport layer, and in contact therewith a metal cathode, wherein the electron transport layer is comprised of an electron transport component comprised of specific triazine compounds.
Specifically, it is a feature of the present invention to provide EL devices comprised of a supporting substrate of, for example, glass, an indium tin oxide anode, a buffer layer comprised of a tertiary aromatic amine optionally doped with an aromatic hydrocarbon such as rubrene, a vacuum deposited organic hole transporting layer comprised of, for example, 4,4xe2x80x2-bis(9-carbazolyl)-1,1xe2x80x2-biphenyl, a vacuum deposited electron transport layer comprised of specific triazine compounds, such as 4,4xe2x80x2-bis-[2-(4,6diphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, and in contact therewith a low work function metal, such as magnesium or aluminum, or their alloys.
Also, it is a feature of the present invention to provide EL devices comprised of a supporting substrate of, for example, glass, an indium tin oxide anode, an optional buffer layer, a vacuum deposited organic hole transporting layer comprised of, for example, N,Nxe2x80x2-di-1-naphthyl-N,Nxe2x80x2-diphenyl-1,1xe2x80x2-biphenyl-4,4xe2x80x2-diamine optionally doped with an aromatic hydrocarbon such as rubrene, a vacuum deposited light-emitting layer comprised of, for example, tris(8-hydroxyquinolinate)aluminum, a vacuum deposited electron transport layer, a vacuum deposited electron transport layer comprised of specific triazine compounds such as 4,4xe2x80x2-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, and in contact therewith a low work function metal, such as magnesium or aluminum, or their alloys.
Aspects of the present invention relate to an electroluminescent device comprised of an anode and a cathode, and situated therebetween the anode and the cathode at least one electron transport layer comprised of a triazine of the formula 
wherein A is a monovalent or a multivalent aromatic group which contains at least two conjugate-linked or at least two fused aromatic rings; Ar1 and A2 are each independently aryl or aliphatic; and m represents the number of repeating segments; an electroluminescent device wherein the A aromatic group is selected from the group consisting of 
wherein R1 to R5 are each independently a substituent selected from the group consisting of hydrogen, aliphatic, a halogen, aliphatic, a halogen atom, and a cyano group; L is a divalent group selected from the group consisting of xe2x80x94C(Rxe2x80x2Rxe2x80x3Hxe2x80x94, alkylene, an oxygen atom, a sulfur atom; and xe2x80x94Si(Rxe2x80x2Rxe2x80x3Hxe2x80x94 wherein Rxe2x80x2 and Rxe2x80x3 are selected from the group consisting of hydrogen, alkyl, alkoxy, and aryl; G is a divalent linkage and each i, j, and k represent the number of repeating groups; an electroluminscent device wherein A contains a biphenyl, a naphthyl or a terphenyl; Ar1 Ar2 are each independently an aryl group selected from the group consisting of a phenyl, a biphenylyl, a naphthyl, and a stilbenyl; and wherein the aryl group optionally further contains a substituent selected from the group consisting of hydrogen, an alkyl group with from 1 to about 6 carbon atoms, an alkoxy group with from 1 to about 6 carbon atoms, a halogen, and a cyano group; an electroluminescent device wherein the triazine compounds are represented by the Formula (II), (III), (IV), or (V) 
wherein Ar1, A2, Ar3, and Ar4 are each independently an aryl; R1 and R2 are substituents selected from the group consisting of hydrogen, an alkyl, an aryl, an alkoxy, a halogen atom, and a cyano; R3 and R4 are each a divalent group L selected from the group consisting of xe2x80x94C(Rxe2x80x2Rxe2x80x3)Hxe2x80x94, alkylene, an oxygen atom, a sulfur atom, and xe2x80x94Si(Rxe2x80x2Rxe2x80x3)xe2x80x94, wherein Rxe2x80x2 and Rxe2x80x3 are selected, for example, from the group consisting of hydrogen, alkyl, alkoxy, and aryl; an electroluminescent device wherein Ar1, A2, A3, and Ar4 are aryl with about 6 to about 36 carbon atoms, and more specifically, are selected from the group consisting of a phenyl, a biphenylyl, a naphthyl, and a stilbenyl; and wherein the aryl group contains a substituent selected from the group consisting of hydrogen, an alkyl group with from 1 to about 12 carbon atoms, an alkoxy group with from 1 to about 6 carbon atoms, a halogen atom, and a cyano group; an electroluminescent device wherein the aryl is selected from the group consisting of a phenyl, a tolyl, a methoxyphenyl, a butylphenyl, a naphthyl, and a biphenylyl; and wherein R1 and R2 are hydrogen or methyl; an electroluminescent device wherein L is xe2x80x94C(Rxe2x80x2Rxe2x80x3)xe2x80x94, wherein Rxe2x80x2 and Rxe2x80x3 is a hydrogen atom, an alkyl group containing from 1 to about 10 carbon atoms, or an alkoxyl group containing from 1 to about 10 carbon atoms; an electroluminescent device wherein the triazine is selected from the group consisting of 2,4,6-tris(4-biphenylyl)-1,3,5-triazine, 2,4,6-tris[4-(4xe2x80x2-methylbiphenylyl)]-1,3,5-triazine, 2,4,6-tris[4-(4xe2x80x2-tert-butylbiphenylyl)-1,3,5-triazine, 2,4,6-tris[4-(4xe2x80x2-methoxybiphenylyl)]-1,3,5-triazine, 4,4xe2x80x2-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6di-p-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4-xcex2-naphthyl-6-phenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 2,7-bis-[2-(4,6-di-phenyl-1,3,5-triazinyl)]fluorene, 2,7-bis-[2-(4,6-di-phenyl-1,3,5-triazinyl)]-9,9-dimethylfluorene, 4,4xe2x80x2-bis-[2-(4,6-di-phenyl-1,3,5-triazinyl)]-stilbene, and 4,4xe2x80x2-bis-[2-(4-phenyl-6-m-tolyl-1,3,5-triazinyl)]-stilbene; an electroluminescent device wherein the triazine is selected from the group consisting of 2,4,6-tris(4-biphenylyl-1,3,5-triazine, 4,4xe2x80x2-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6di-m-tolyl-1,3,5-triazinyl-)]-1,1-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-tert-butylphenyl-1,3,5triazinyl)]-1,1xe2x80x2-biphenyl, and 4,4xe2x80x2-bis-[2-(4,6-di-phenyl-1,3,5-triazinyl)]stilbene; an electroluminescent device comprised of, in sequence, an anode, an optional buffer layer, a hole transport layer, an electron transport layer, and in contact therewith a cathode, wherein the electron transport layer contains an electron transport component comprised of a triazine compound or compounds encompassed by the formula 
wherein A is an aromatic group which contains at least two conjugate-linked or two fused aromatic rings; Ar1 and Ar2 are each independently aryl or aliphatic; and m represents the number of repeating segments; an electroluminescent device wherein the A group is selected from the group consisting of 
wherein R1 to R5 are each independently a substituent selected from the group consisting of hydrogen, aliphatic, a halogen atom, and a cyano group; L is a divalent group selected from the group consisting of xe2x80x94C(Rxe2x80x2Rxe2x80x3)xe2x80x94, alkylene, an oxygen atom, a sulfur atom; and xe2x80x94Si(Rxe2x80x2Rxe2x80x3)xe2x80x94 wherein Rxe2x80x2 and Rxe2x80x3 are selected from the group consisting of hydrogen, alkyl, alkoxy, and aryl; G is a divalent linkage and each i, j, and k represent the number of repeating groups; an electroluminescent device which contains a biphenyl, a naphthyl or a terphenyl; Ar1 and Ar2 are each independently an aryl group selected from the group consisting of a phenyl, a biphenylyl, a naphthyl, and a stilbenyl; wherein the aryl group optionally further contains a substituent selected from the group consisting of hydrogen, an alkyl group, an alkoxy group, a halogen, and a cyano group; an electroluminescent device wherein there is selected a triazine compound represented by the Formula (II), (III), (IV), or (V) 
wherein Ar1, A2, A3, and Ar4 are each independently alkyl or preferably aryl; R1 and R2 are substituents selected from the group consisting of hydrogen, an alkyl, an aryl, an alkoxy, a halogen atom, and cyano; L is a divalent group selected from the group consisting of xe2x80x94C(Rxe2x80x2Rxe2x80x3)xe2x80x94, alkylene, an oxygen atom, a sulfur atom, and xe2x80x94Si(Rxe2x80x2Rxe2x80x3)xe2x80x94, wherein Rxe2x80x2 and Rxe2x80x3 are each selected from the group consisting of hydrogen, alkyl, alkoxy, and aryl; an electroluminescent device wherein Ar1, A2, Ar3, and Ar4 are selected from the group consisting of phenyl, biphenylyl, naphthyl, and stilbenyl; wherein the aryl group further contains a substituent selected from the group consisting of hydrogen, an alkyl group with from 1 to about 10 carbon atoms, an alkoxy group with from 1 to about 10 carbon atoms, a halogen atom, and a cyano group; an electroluminescent device wherein the aryl is selected from the group consisting of a phenyl, a tolyl, an methoxyphenyl, a butylphenyl, a naphthyl, and a biphenylyl; wherein R1 and R2 are hydrogen or methyl; an electroluminescent device wherein L is xe2x80x94C(Rxe2x80x2Rxe2x80x3)xe2x80x94, wherein Rxe2x80x2 and Rxe2x80x3 is a hydrogen atom, an alkyl group containing from 1 to about 6 carbon atoms, or an alkoxyl group containing from 1 to about 6 carbon atoms; an electroluminescent device wherein the hole transport layer or the electron transport layer is a light emitting layer; an electroluminescent device wherein the buffer layer is comprised of a phthalocyanine or derivatives thereof, a tertiary aromatic amine, a polyaniline, or a polythiophene; an electroluminescent device wherein the buffer layer is comprised of the tertiary aromatic amine N,Nxe2x80x2,N,Nxe2x80x2-tetraarylbenzidine, optionally doped with an aromatic polycyclic hydrocarbon stabilizer of rubrene or a 9,10-diphenylanthracene, wherein the stabilizer is present in an amount of from about 0.5 to about 10 weight percent, based on the weight of the tertiary aromatic amine, and the stabilizer; an electroluminescent device further containing a light emitting layer situated between the hole transport layer and the electron transport layer; an electroluminescent device wherein the light emitting layer is comprised of a metal chelate compound of an 8-hydroxyquinoline, or a stilbene derivative; an electroluminescent device wherein the light emitting layer further contains a fluorescent dye; an electroluminescent device wherein the fluorescent dye is selected from the group consisting of coumarins, quinacridones, and aromatic hydrocarbon fluorescent dyes; an electroluminescent device wherein the fluorescent dye is present in an amount of from about 10xe2x88x923 to about 10 mole percent based on the moles of the light emitting layer material; an electroluminescent component wherein there is selected a triazine compound selected from the group consisting of 2,4,6-tris(4-biphenylyl)-1,3,5-triazine, 2,4,6-tris[4-(4xe2x80x2-methylbiphenylyl)]-1,3,5-triazine, 2,4,6-tris[4-(4xe2x80x2-tert-butylbiphenylyl)-1,3,5-triazine, 2,4,6-tris[4-(4xe2x80x2-methoxybiphenylyl)]-1,3,5-triazine, 4,4xe2x80x2-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4-xcex2-naphthyl-6-phenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 2,7-bis-[2-(4,6-di-phenyl-1,3,5-triazinyl)]fluorene, 2,7-bis-[2-(4,6-di-phenyl-1,3,5-triazinyl)]-9,9-dimethyl fluorene, 4,4xe2x80x2-bis-[2-(4,6-di-phenyl-1,3,5-triazinyl)]-stilbene, and 4,4xe2x80x2-bis-[2-(4-phenyl-6-m-tolyl-1,3,5-triazinyl)]-stilbene; an electroluminescent compound wherein there is selected a triazine compound selected from the group consisting of 2,4,6-tris(4-biphenylyl)-1,3,5-triazine, 4,4xe2x80x2-bis-[2-(4,6-diphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-m-tolyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-[2-(4,6-di-p-methoxyphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, 4,4xe2x80x2-bis-12-(4,6-di-p-tert-butylphenyl-1,3,5-triazinyl)]-1,1xe2x80x2-biphenyl, and 4,4xe2x80x2-bis-[2-(4,6-di-phenyl-1,3,5-triazinyl)]-stilbene; an electroluminescent device wherein the anode is comprised of an indium tin oxide, and the cathode is comprised of a low work function metal; an electroluminescent device wherein the low work function metal is lithium, magnesium, aluminum, or each of the alloys thereof; an organic electroluminescent device comprising in the following sequence an anode comprised of indium tin oxide in a thickness of from about 1 to about 500 nanometers, including 90 nanometers, an optional buffer layer comprised of a phthalocyanine or a stabilized tertiary aromatic amine and which buffer layer is of a thickness of from about 5 to about 300 nanometers, including 90 nanometers, a hole transport layer comprised of a tertiary aromatic amine and which layer is of a thickness of about 1 to about 200 nanometers, including 90 nanometers, a triazine electron transport layer of a thickness of from about 5 to about 300 nanometers, including 90 nanometers, and a cathode comprised of a low work function metal and which cathode is of a thickness of from about 10 to about 800 nanometers and wherein the triazine is of the formula 
wherein A is aromatic which contains at least two conjugate-linked or two fused aromatic rings; Ar1 and Ar2 are each independently aryl or aliphatic; and m represents the number of repeating segments; an organic electroluminescent device wherein the anode is of a thickness of from about 30 to about 100 nanometers, the buffer layer is present and is comprised of a phthalocyanine or a stabilized tertiary aromatic amine and which a layer is of a thickness of from about 10 to about 200 nanometers, a light emitting layer in contact with the hole transport layer and comprised of an 8-hydroxyquinoline metal chelate or a stilbene derivative and which layer is of a thickness of from about 1 to about 500 nanometers; an organic electroluminescent device comprised of an anode, an organic luminescent medium, and a cathode, wherein the organic luminescent medium contains a triazine layer in contact with the cathode, which layer is comprised of the triazine compounds of Formula (1), and wherein the triazine functions as an electron transport, an electron injector, or simultaneously as an electron transport and an electron injector 
wherein A is a monovalent or a multivalent aromatic group which contains at least two conjugate-linked or at least two fused aromatic rings; Ar1 and Ar2 are each independently aryl or aliphatic; and m represents the number of repeating segments; an organic electroluminescent device wherein the cathode is comprised of lithium, magnesium, aluminum, or their alloys; an organic electroluminescent device wherein the cathode is comprised of aluminum; an organic electroluminescent device wherein there is selected a triazine represented by the Formula (II), (III), (IV), or (V) 
wherein the substituents are as illustrated herein; an electroluminescent device comprised of an anode, a cathode, and a triazine compound of the formula 
wherein A is a monovalent aromatic group or a multivalent aromatic group which contains from about 2 to about 15 two conjugate-linked or from about 2 to about 15 fused aromatic rings; Ar1 and Ar2 are each independently aryl or aliphatic; and m represents the number of repeating segments and is a number of from 1 to about 4, and wherein the triazine functions as an electron transport, an electron injector, or simultaneously as an electron transport and an electron injector; an organic electroluminescent device wherein the anode is of a thickness of from about 30 to about 100 nanometers, the buffer layer is of a thickness of from about 10 to about 100 nanometers, the hole transport is of a thickness of from about 5 to about 100 nanometers, the triazine electron transport layer is of a thickness of from about 10 to about 100 nanometers, and the cathode is of a thickness of from about 50 to about 500 nanometers, and wherein the low is from about 2 to about 4 electron volts, and wherein Ar1 and Ar2 are each independently aryl; an organic electroluminescent device wherein the anode is of a thickness of from about 30 to about 100 nanometers, the buffer layer is of a thickness of from about 10 to about 100 nanometers, the hole transport layer is comprised of a tertiary aromatic amine in a thickness of about 5 to about 100 nanometers, thereover a light emitting layer comprised of an 8-hydroxyquinoline metal chelate or a stilbene derivative of a thickness of from about 10 to about 100 nanometers, the triazine electron transport layer is of a thickness of about 10 to about 100 nanometers, and the cathode is of a thickness of from about 50 to about 500 nanometers; an electroluminescent device wherein the triazines R1 to R5 are each alkyl, alkoxy, or mixtures thereof; alkyl for the Rxe2x80x2 and Rxe2x80x3 contains from 1 to about 25 carbon atoms; and each of the i, j and k represent a number of from 1 to about 3; an electroluminescent device wherein at least one is from 1 to about 10; an electroluminescent device wherein the at least one is from 1 to about 3; an electroluminescent device wherein the at least two is from 2 to about 7, and electron transport electron injection, or mixtures thereof, components comprised of the triazine compounds illustrated by the formula 
wherein Ar1 and Ar2 are independently aromatic, such as an aryl group, and which aryl can, for example, be selected from the group consisting of a phenyl, a stilbenyl, a biphenylyl, a naphthyl, a pyridyl, and a quinolyl and the like, and wherein the aryl group may further contain a substituent selected from the group consisting of hydrogen, an alkyl group with, for example, from 1 to about 10 carbon atoms, an alkoxy group with, for example, from 1 to about 10 carbon atoms, a dialkylamino group with preferably from about 1 to about 3 carbon atoms, a halogen, a cyano group and the like; m is a number of from 1 to about 4; and A is a monovalent or a multivalent aromatic group which contains at least two conjugate-linked or two fused aromatic rings, such as from about 2 to about 10.
Examples of monovalent or multivalent groups A are 
wherein R1 to R5 are each independently a substituent preferably selected from the group consisting of hydrogen aliphatic, such as an alkyl group, an alkoxy group, a halogen such as a chloride atom, a cyano group, and the like; L is a divalent group which may be selected from the group consisting of xe2x80x94C(Rxe2x80x2Rxe2x80x3)xe2x80x94, an ethylene, xe2x80x94Si(Rxe2x80x2Rxe2x80x3)xe2x80x94, an oxygen atom, a sulfur atom, and the like, wherein Rxe2x80x2 and Rxe2x80x3 is a hydrogen atom, an alkyl group containing from 1 to about 10 carbon atoms, or an alkoxyl group containing from 1 to about 10 carbon atoms, or an aryl; G is a divalent linkage, which may be selected from the group consisting of xe2x80x94C(Rxe2x80x2Rxe2x80x3)xe2x80x94, an alkylene like ethylene, xe2x80x94Si(Rxe2x80x2Rxe2x80x3)xe2x80x94, an oxygen atom, a sulfur atom, and the like, preferably L is xe2x80x94C(Rxe2x80x2Rxe2x80x3)xe2x80x94, wherein Rxe2x80x2 and Rxe2x80x3 is a hydrogen atom, an alkyl group containing from 1 to about 5 carbon atoms, or an aryl; and i, j, k are a number of from 1 to about 3.
A particularly preferred class of triazine components or compounds are illustrated by the following formula 
wherein Ar1 and Ar2 are each independently aryl, and aryl can be selected, for example, from the group consisting of a phenyl, a stilbenyl, a biphenyl, a naphthyl, a pyridyl, and a quinolyl and the like, and wherein the aryl group may further contain a suitable substituent selected, for example, from the group consisting of hydrogen, an alkyl group, an alkoxy group, a dialkylamino, a halogen, a cyano group and the like; R1 and R2 are, for example, substituents selected from the group consisting of hydrogen, aliphatic such as an alkyl group, and an alkoxy group; a halogen such as a chloride atom, a cyano group, and the like.
Another preferred class of triazine components or compounds are illustrated by the following formula 
wherein Ar1, Ar2, Ar3, and Ar4; and the substituents of R1 and R2 are as indicated herein. The compounds of Formula (III) may further contain a linkage, and more specifically, be of the formula represented by 
wherein the aryl groups of Ar1, Ar2, Ar3, and Ar4, and the substituents of R1 and R2 are as indicated herein; L is a divalent group which may be selected from the group consisting of xe2x80x94C(Rxe2x80x2Rxe2x80x3)xe2x80x94, an alkylene like ethylene, xe2x80x94Si(Rxe2x80x2Rxe2x80x3)xe2x80x94, an oxygen atom, a sulfur atom, and the like, wherein Rxe2x80x2 and Rxe2x80x3 is a hydrogen atom, an alkyl group preferably containing from 1 to about 10 carbon atoms, or an alkoxyl group preferably containing from 1 to about 10 carbon atoms; or L is R3 and R4 as illustrated herein.
Yet another preferred class of triazine components or compounds are illustrated by the following formula 
wherein the aryl groups of Ar1, Ar2, Ar3, and Ar4; and the substituents of R1 and R2 are as illustrated herein.
In embodiments, the present invention relates to organic EL devices that are comprised of a supporting substrate of, for example, glass, an anode, an organic luminescent medium or layer in contact with a cathode, wherein the organic luminescent layer contains an electron transport component comprised of the triazines illustrated herein. In a preferred embodiment, the organic luminescent medium is comprised of an optional buffer layer, an organic hole transport layer, and an electron transport layer comprised of the triazine compound illustrated herein, wherein either of the hole transport layer or the electron transport layer may serve as a light emitting layer. In another preferred embodiment, the organic luminescent medium is comprised of a buffer layer, an organic hole transport layer, a light-emitting layer, and an electron transport layer comprised of the triazine compounds illustrated herein, and wherein the light emitting layer may further contain a fluorescent material capable of emitting light in response to energy released by the hole-electron recombination.
The triazine compounds of the present invention which can readily be evaporated to deposit thin films with desirable morphological and thermal stability exhibit acceptable to excellent electron transport properties, and excellent chemical and electrical stability.
In embodiments, such as where the triazine compound preferably of formulas (II) to (V), are selected as an electron transport component, the organic EL devices of the present invention can provide a number of improved performance characteristics, such as high luminance, low driving voltages, long device operation stability and extended useful durability, the enablement of light emission from about 400 nanometers to about 700 nanometers, and the use of a cathode comprised of a metal such as aluminum.